In a functionally differentiated world society, there is no real equilibrium. So when people say things like “We can balance economic growth with environmental protection” they are just kidding themselves. What they really mean is that we can have economic growth without causing excessive damage to the natural environment; then we have to talk about what excessive damage means. But we can’t honestly claim that we aren’t damaging (or at least destabilizing) the natural environment.
The equilibrium model cannot handle complexity. It belongs to a mechanistic worldview. But when we deal with autopoietic systems, structurally coupling, and irritation, we’re not talking about balance. The economy, for instance, can irritate and even destroy other systems, but there can never be a balance between systems. Society, understood as a vast system of communication, can irritate and even destroy all life on this planet, but there can’t be any balance. There cannot be balance between a system and its environment. As in any two-sided form, the marked and unmarked sides are not balanced. One side is ignored or not seen.
Along with irritation, we can speak of “disturbance,” as in saying that a system may be disturbed by its environment. But, as Luhmann argues,
If one uses the term “disturbance,” one must be clear about the fact that one is no longer dealing with a theory of equilibrium. Theories of equilibrium or balance had also included the concept of disturbance. In fact, the entire model had been formulated in two directions in terms of disturbances. On the one hand, there was the easiness or probability of disturbance. If you think of scales, it takes very little force, just a few added grams to one side, to disturb the balance. [These ideas] emerged in the seventeenth century and concerned the artificiality of the balance or trade or the international balance of power. But on the other hand, one always imagined that the equilibrium has a sort of infrastructure or apparatus at its disposal that serves it self-maintenance. As a consequence, a disturbance leads to the reconstitution of the equilibrium. . . . In principle, however, the meaning of this model, which, to be sure, is really a metaphor, was to earmark equilibrium as a stable system. Or . . . one might say that, in such a model, the maintenance of the system structure is tied to the concept of equilibrium. (Introduction to Systems Theory, p. 88-89)
Instead of stability guaranteed by balance, we can speak of stabilization, destabilization, and re-stabilization. In this way, we can account for the evolution of dynamic systems (e.g., population). In this sense, the linkage of stability with equilibrium doesn’t work anymore. As Luhmann writes,
Today this linkage has become questionable in several respects. On the one hand, in natural science the prevalent idea is that it is precisely imbalance which can be stable, and in economics a system is said to be stable if either too many goods are on offer and there are too few buyers or, vice versa, if there are too many buyers and not enough goods. . . . This tendency puts the old model in doubt. If, on the other hand, one proceeds from ideas of autopoiesis, operational closure, and structural coupling, the balance model becomes questionable simply because one would have to regard imbalances and balances as functional equivalents, since both serve to maintain stability. . . . Now, the question is how a disturbance can be conceptualized internally within the system if one does without the equilibrium model. (p. 89)
We can think in terms of information processing. Irritations, perturbations, or disturbances cause destabilization, which must be followed up by restabilization. Stable systems consist of structures (or structural patterns) and a range of possible operations. The irritation (or whatever we call it) can become information within the system and for the system.
A disturbance, a piece of information, or an irritation provides the system with a relevant choice from a range of possibilities. Such an occurrence can initiate search or identification processes. (89)
In self-referential systems, structures are patterns of expectations, and these expectations constrain the range of possible interpretation. If we hear some kind of music (or a sound pattern that resembles music as we know it), we won’t interpret it as a dog barking. We identify the sound pattern as music. We might then search to identify the kind of music it is. The speed at which we can do this is restrained by the capacity of the system. As Luhmann puts it,
the range of interpretive possibilities corresponds to the speed and the information processing capacity of the system.
“Disturbance” therefore means the initiation of information processing that can be handled operationally in the system. . . The concept of disturbance is thus detached from the equilibrium model and adapted in order to described something that could better be called an information-processing process [Informationsverarbeitungsprozess].
A population, such the domestic cat (Felis catus), can be understood as a gene pool, which we can also call a closed, autopoietic system. Such a system can process information internally if it is irritated by its environment. But this is not the same as maintaining equilibrium in the gene pool. Where there is equilibrium, there is no evolution.